Exception ref is not part of the latest exception handling
proposal. Remove the corresponding value type, the type opcode and some
obsolete tests.

R=clemensb@chromium.org

Bug: v8:8091
Change-Id: I5e068ba3426f4b56b90ef056193acdd8cc8fe7d7
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2632599Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72116}